Communication systems continue to grow and evolve. Convergence between different types of communication systems, e.g., Internet Protocol (IP), connection-based voice communications, and the like, is advancing rapidly. Recently the phrase “Next Generation Network” (NGN) has been used to describe various activities associated with this evolution. As defined by the International Telecommunications Union (ITU), an NGN is a packet-based network able to provide services (including telecommunication services) and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies. NGNs will also likely offer unrestricted access by users to different service providers and will support generalized mobility, which in turn will provide for consistent service provision to end users.
So called “Web Services” are another feature which may become commonplace in NGNs. Web Services provide, for example, a mechanism for interoperability between software entities which reside on different infrastructures and which may be operated by different companies. Web Services are typically defined as providing distributed services using, e.g., the standards suite Web Services Description Language (WSDL), Simple Object Access Protocol (SOAP) and Universal Description, Discovery and Integration (UDDI). For the interested reader, a description of WDSL can be found online as “Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language, W3C Working Draft 3, Aug. 2004” at http://www.w4.org/TR/2004/WD-wsdl120-20040803/, the disclosure of which is incorporated here by reference. Similarly, a description of SOAP can be found online as “SOAP Version 1.2 Part 0: Primer (Second Edition), W3C Recommendation 27 Apr. 2007” at http://www.w3.org/TR/soap12-part0/, the disclosure of which is incorporated by reference. Additionally, for UDDI, a standards document entitled “UDDI Version 3.0.2 UDDI Spec Technical Committee Draft, Dated Oct. 19, 2004”can be found at http://uddi.org/pubs/uddi_v3.htm, the disclosure of which is incorporated here by reference.
Web Services can be characterized as a technology for exposing application functionality as services to software clients or to server applications. Among other things, Web Services allow for rapid creation of new services by combining existing functionality in new ways. This process is often referred to as composition or orchestration. Typically, Web Services are accessed with XML-encoded SOAP messages using hyper-text transfer protocol (HTTP) as a bearer. However, HTTP is designed for transaction based client/server request patterns where real time properties are not required. Consider in this regard the variable, and sometimes extensive, delays which can occur when a user retrieves a web page by clicking on an HTTP hyperlink. With the increasing demand for service interaction and rapid composition from the users of peer to peer, real-time communication services, there is a need to also apply the Web Services paradigm to this real-time domain.
Moreover, such efforts also do not take explicit intermediary addressing into consideration. On the contrary, existing work either considers SIP service addressing to be applicable for application launch only, e.g., by letting the application use a second protocol (e.g., HTTP) to perform actual method invocation, or is basing service addressing on SIP routing only, which provides a crude way of involving intermediary services into the session initiation sequence. This makes existing SIP service addressing based on capabilities ill-equipped to implement real-time service composition. Additionally, once available, it would be desirable to provide techniques and mechanisms for allowing users to discover and/or subscribe to such real-time services.
Accordingly, it would be desirable to address this need by providing service subscription techniques associated with real-time composition of services in communications systems.